The present invention relates generally to a system for monitoring levels of a sterilant during a sterilization process, and more particularly to a self-contained monitoring assembly configured to monitor hydrogen peroxide (H2O2) vapor levels during sterilization of articles such as packages, vessels, machines or the like.
Aseptic processing of consumable goods, such as nutritional compounds and food products, is typically effected by separate sterilization of the contents and the containers within which the contents are packaged. Subsequent to separate sterilization, the contents are placed in the containers and sealed in a sterile environment for shipment, storage and use.
Sterilization of such containers prior to contacting the desired sterilized contents can be performed efficiently by use of a sterilant such as hydrogen peroxide (H2O2) vapor. In such a process, the containers are introduced into a sterilization apparatus in which the containers are flushed with hydrogen peroxide vapor. The containers are subsequently flushed with warm air or any other fluid suitable to achieve desirably low levels of residual hydrogen peroxide. This general procedure is highly effective in achieving sterilization of the containers, and likewise can be performed on any other suitable articles that will come into contact with the desired compound.
Notwithstanding the effectiveness of hydrogen peroxide (H2O2) sterilization, accurate monitoring of H2O2 vapor concentration levels can be problematic. This is due in part to the physical and chemical property changes of hydrogen peroxide vapor under processing conditions, and further due to decomposition upon contact with surfaces of various materials within the processing area.
As such, undesired deviation of hydrogen peroxide vapor concentration, and excessive decomposition, can result in loss of sterility of the containers and surrounding aseptic processing area. By contrast, hydrogen peroxide vapor is corrosive in nature, and thus excessive concentration levels can result in detrimental effects to the surrounding equipment and surfaces. Furthermore, and in accordance with government standards, low residual sterilant levels must be maintained for subsequent use of the sterilized containers.
Heretofore, hydrogen peroxide vapor detection systems have been undesirably bulky, as exemplified by conventional near infrared (NIR) analysis apparatus. Additionally, known off-line testing is typically too slow to monitor sterilant levels with sufficient accuracy. Previous arrangements have not provided xe2x80x9creal timexe2x80x9d monitoring throughout an aseptic processing cycle, and particularly have not been capable of monitoring hydrogen peroxide vapor concentrations within a container or like article as it is sterilized.
The present sterilant monitoring system, and the self-contained assembly thereof, overcomes these deficiencies in the prior art by providing a highly accurate, cost effective arrangement for providing real-time monitoring of a sterilant, such as hydrogen peroxide vapor, and is configured to facilitate monitoring of the sterilant levels throughout the processing cycle of a sterilization apparatus.
The purpose and advantages of the present invention will be set forth in and apparent from the description that follows, as well as will be learned by practice of the invention. Additional advantages of the invention will be realized and attained by the methods and systems particularly pointed out in the written description and claims hereof, as well as from the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described, the invention includes a sterilant monitoring system particularly suited for monitoring concentrations of a sterilant, such as hydrogen peroxide (H2O2) vapor, as used by a sterilization apparatus. The system includes a self-contained monitoring assembly that can be readily positioned proximate the sterilization apparatus. It is particularly contemplated that the monitoring assembly be positioned within a carrier element configured as one of the articles to be sterilized by the sterilization apparatus. In this manner, the sensor structure can be moved through the sterilization apparatus so as to monitor sterilant concentration levels throughout a processing cycle.
In accordance with the illustrated embodiment, the present sterilant monitoring system is particularly configured for a sterilization apparatus using a sterilant such as hydrogen peroxide vapor. Further in accordance with the invention, and as embodied herein, the system uses a sterilant monitoring assembly for data collection purposes. The sterilant monitoring assembly includes a sterilant sensor configured to provide output signals corresponding to detected levels of the sterilant. The sterilant sensor preferably includes a gas-detecting semi-conductor element, and a heating element operatively associated therewith to elevate the temperature of the gas-detecting semi-conductor element to an appropriate operating temperature. A data collection circuit is operatively coupled to the sterilant sensor to receive the output signals from the sensor as collected data, with the assembly including a power source to provide electrical power to the sensor and the data collection circuit as needed. In the preferred form, a temperature sensor also is operatively connected to the data collection circuit to provide output signals corresponding to the ambient temperature proximate the sterilant sensor for collection in combination with the output signals from the sterilant sensor. In this manner, the temperature data may be used as a reference to correlate more accurately the sensor output signals with corresponding H2O2 vapor concentration levels.
The sterilant monitoring assembly of the present invention is configured as a self-contained, portable unit. That is, the sterilant sensor, data collection circuit, and power source, as well as the preferred temperature sensor, are self-contained on a portable structure so as to be freely positionable proximate the sterilization apparatus to monitor levels of sterilant thereat. In a preferred form, the portable structure is mounted on a carrier element configured as an article to be sterilized by the sterilization apparatus, such as a container or like article.
In accordance with the invention, collected data can be processed by configuring the monitoring system as a whole, and the data collection circuit particularly, in any of a variety of different arrangements. In one arrangement of the invention, the data collection circuit includes an electronic memory to create a readable memory of the data collected during a selected time interval.
The assembly of this arrangement may include a signal connector, such as data port or a transmitter, to allow transfer of signals representative of the collected data from the electronic memory to a remote communication unit that is joined in communication with the signal connector.
In this manner, the collected data can be transferred or downloaded to a processor, which forms a part of the sterilant monitoring system as a whole. Once downloaded, the collected data can thereafter be stored, graphically displayed in various forms, or otherwise analyzed and processed to identify and monitor the detected sterilant concentration levels.
Alternatively, or additionally, the monitoring assembly may be configured to transmit remotely the collected data simultaneous with collection to a remote communication unit positioned exteriorly of the sterilization apparatus. In this configuration, the data collection circuit of the monitoring assembly preferably includes a transmitter to transmit signals representative of the collected data to a remote communication unit. Radio frequency or near infrared transmission are presently preferred for such remote transmission. If desired, an electronic memory and physical signal connector also may be provided in combination with the transmitter for back-up purposes.
As will be appreciated, sterilization processing typically entails the passage of articles through a sterilization apparatus, with attendant variations in temperature and sterilant concentrations during the process. It is desirable to collect data corresponding to selected intervals or conditions during the processing cycle. The present monitoring assembly therefore may also include a circuit to select certain conditions, such as time or temperature, for data collection, and a signal connector or a control device to allow entry of such selected conditions.
In order to effect data collection in a manner that accurately corresponds to the processing conditions to which articles are subjected by the sterilization apparatus, the present monitoring system preferably includes a carrier element for mounting the self-contained portable structure of the monitoring assembly thereon. Preferably, the carrier element is configured as an article similar to that to be sterilized by the apparatus. In the illustrated embodiment, this carrier element is configured as a container having a shape and dimensions essentially the same as containers normally sterilized in the apparatus. Notably, the carrier element is configured such that the portable structure can be positioned inside the carrier element, thus providing data collection corresponding to conditions within a container during the sterilization process.
Other features and advantages of the present invention will become readily apparent from the following detailed description, the accompanying drawings, and the appended claims.